This invention relates to a two stage process for the production of molded articles by the reaction of an organic polyisocyanate, organic polyepoxide and special catalysts.
Reactive mixtures composed of organic polyisocyanate, organic polyepoxide and special catalysts give rise to synthetic resins with isocyanurate and oxazolidinone structures. They may be prepared by the polyaddition of polyfunctional 1,2-epoxides with polyisocyanates and hardening catalysts (See, e.g., No. EP-A-0,130,454, DE-OS No. 3,323,084 or DE-OS No. 3,323,153).
In an earlier German patent application (No. P 36 00 764.1), the two stage production of molded products based on organic polyisocyanates and organic polyepoxides with tertiary or quaternary ammonium salts of alkylating or acid esters of organic phosphonic acids or of phosphoric acid as catalysts is disclosed. The intermediate "B-state" is obtained in that disclosed process by cooling the reaction mixture and thereby virtually stopping the reaction. The systems disclosed in this earlier application may be converted into the crosslinked, no longer fusible state at a later date by reheating.